the effects of thyme extrac (thymus vulgaris) on systemic antibody responses against influenza and newcastle disease vaccine in broiler chickens

background & aim: the recent study was conducted to investigate the effects of thyme extract in drinking water on immune response of broiler chickens. experimental:  a total of 245 day-old broiler chicks were purchased and 20 chicks were bled for determination maternal antibody and remaining chicks divided into 5 equal groups. chickens of group a, b and c received 0.1%, 0.15% and 0.2% ofthyme extract in drinking water for all of the period of experiment, respectively. chickens of group d did not receive thyme extract but vaccinated against newcastle and influenza diseases. chickens of group e were kept as control group and did not receive thyme extract and newcastle and influenza diseases vaccines. chickens of group a, b, c and d were vaccinated with live newcastle vaccine (b1 strain) intraocularly and ai-nd killed vaccine (subtype h9n2) subcutaneously of neck back. blood samples were collected before vaccination as well as on days 14, 28 and 35 after vaccination. ten chickens of each group were bled randomly and antibody titer against newcastle and influenza vaccine virus was determined by hi test. results & discussion: the results of present study showed that thyme extract has no effect on antibody response against newcastle vaccine virus, but 14 days after vaccination, receiving of 0.2% ofthyme extract, significantly increased the specific antibody response against influenza vaccine virus compared to all groups. industrial and practical recommendations: herbs that are rich in flavonoids such as thyme (thymus vulgaris) extend the activity of vitamin c, act as antioxidants and may therefore enhance the immune function.